Prebiotics in Inflammatory Bowel Diseases

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British Journal of Nutrition (2007), 98, Suppl. 1, S85–S89 doi: 10.1017/S0007114507832958 q The Author 2007

https://www.cambridge.org/core

Prebiotics in inﬂammatory bowel diseases

Francisco Guarner*

Digestive System Research Unit, Ciberehd University Hospital Vall d’Hebron, Passeig Vall d’Hebron, 119-129 08035 . IP address: Barcelona, Spain

170.106.33.14

In genetically susceptible individuals, an altered mucosal immune response against some commensal bacteria of the gut ecosystem appears to be the principal mechanism leading to intestinal lesions in inﬂammatory bowel disease (IBD). The information currently available does not provide an

exact explanation about the origin of this important dysfunction of the interaction between host and commensal bacteria, but an altered microbial , on composition has been detected in the gut ecosystem of patients with Crohn’s disease or ulcerative colitis. Prebiotics are food ingredients

02 Oct 2021 at 05:32:58 not digested nor absorbed in the upper intestinal tract that are fermented by intestinal bacteria in a selective way promoting changes in the gut ecosystem. Experimental and human studies have shown that inulin and oligofructose stimulate saccharolysis in the colonic lumen and favour the growth of indigenous lactobacilli and bifidobacteria. These effects are associated with reduced mucosal inflammation in animal models of IBD. Strong experimental evidence supports the hypothesis that inulin and oligofructose can offer an opportunity to prevent or mitigate intestinal inflammatory lesions in human Crohn’s disease, ulcerative colitis, and pouchitis. Encouraging results have been obtained in preliminary clinical trials.

, subject to the Cambridge Core terms of use, available at ulcerative colitis: Crohn’s disease: pouchitis: inulin: oligofructose: lactulose: animal models of IBD: microbiota

The term ‘inflammatory bowel disease’ (IBD) refers mainly to The gut microbiota three separate clinical entities: Crohn’s disease, ulcerative The term “microflora” or “microbiota” refers to the commu- colitis and pouchitis. These diseases are characterized by per- nity of living micro-organisms assembled in a particular sistent mucosal inflammation at different levels of the gastro- ecological niche of a host individual. The human gut is the intestinal tract. Typically, IBDs exhibit undulating activity natural habitat for a large, diverse and dynamic population with bouts of uncontrolled, chronic mucosal inflammation, fol- of micro-organisms which over millennia have adapted to lowed by remodelling processes that occur during periods of live on the mucosal surfaces or in the lumen8. The number remission. Incidence of such diseases has been growing stea- of resident bacteria increases along the small bowel, from dily during the past 5 decades in Western Europe, and is 4 7 British Journal of Nutrition approximately 10 in the jejunum to 10 colony-forming now expanding dramatically in Asian and Eastern European 1 units per gram of luminal content in the distal ileum. The countries . IBDs are becoming an important burden also in https://www.cambridge.org/core/terms large intestine is the most heavily populated region of intes- young populations2. tine, where several hundred grams of bacteria are harboured The precise aetiologies of these chronic inflammatory con- at densities around 1012 colony forming units per gram of ditions remain to be elucidated, but the most important patho- luminal content. physiological mechanisms that lead to the mucosal Our current knowledge about the microbial composition of inflammatory lesions are being unveiled. These mechanisms the intestinal ecosystem in health and disease is still very lim- result from complex interaction of environmental, genetic ited. Studies using classical techniques of microbiological cul- and immunoregulatory factors. Abnormal communication between gut microbial communities and the mucosal ture can only recover a minor fraction of faecal bacteria. Over 50 % of bacteria cells that are observed by microscopic exam- immune system has been suggested as the core defect leading 9 3 ination of faecal specimens cannot be grown in culture . Mol-

to IBD in genetically susceptible individuals . Within the gas- . trointestinal tract, the inflammatory capacity of commensal ecular biological techniques based on the sequence diversity https://doi.org/10.1017/S0007114507832958 of the bacterial genome are being used to characterize non- bacteria is varied. Some resident bacteria are proinflamma- 10 tory, whereas others attenuate inflammatory responses4–6. cultivable bacteria . Molecular studies on the faecal micro- Prebiotics such as inulin and oligofructose can improve the biota have highlighted that only 7 of the 55 known divisions microbial balance in the human gut microbiota by increasing or superkingdoms of the domain ‘bacteria’ are detected in the number and activity of bacteria associated with health the human gut ecosystem, and of these, 3 bacterial divisions benefits7. This article reviews experimental and clinical evi- dominate, i.e. Bacteroidetes, Firmicutes and Actinobacteria. dence supporting the use of prebiotics for the prevention However, at species and strain level, microbial diversity and control of IBD. between individuals is highly remarkable up to the point

* Corresponding author: Francisco Guarner, fax þ 34 934894456, email [email protected] Downloaded from

S86 Francisco Guarner

that each individual harbours his or her own distinctive pattern a metagenomic approach for exhaustive investigation of bac- https://www.cambridge.org/core of bacterial composition10. terial diversity in Crohn’s disease and found a striking reduction On the other hand, studies comparing animals bred under of Firmicutes in patients in remission compared with healthy germ-free conditions with their conventionally raised counter- controls (Fig. 1). parts have clearly demonstrated the important impact of resi- Studies on mucosa-associated bacteria have found high dent bacteria on host physiology. The interaction between gut concentrations of adherent bacteria in patients with clinically bacteria and their host is a symbiotic relationship mutually active ulcerative colitis or Crohn’s disease, but not in healthy beneﬁcial for both partners. The host provides a nutrient- controls20. The concentrations of mucosal adherent bacteria

rich habitat and the bacteria confer important benefits to the increased progressively with the severity of mucosal inflam- . IP address: host8. Functions of the microbiota include nutrition (fermen- mation, and the identified bacteria were of faecal origin. The tation of nondigestible substrates that results in production of fluorescent in situ hybridization (FISH) technique demon- short chain fatty acids, absorption of ions, production of ami- strated bacterial invasion of the mucosa in most mucosal speci- noacids and vitamins), protection (the barrier effect that pre- mens from ulcerative colitis and Crohn’s disease patients, but 170.106.33.14 vents invasion by alien microbes), and trophic effects on the not in any of the mucosal specimens from controls21. Invading intestinal epithelium and the immune system (development bacteria belonged to a great variety of genera, including Pro-

and homeostasis of local and systemic immunity). teobacteria, Enterobacteriaceae, Bacteroides/Prevotella clus- , on

Animals bred in a germ-free environment show low den- ter, Clostridium, and sulphate-reducing bacteria. However, 02 Oct 2021 at 05:32:58 sities of lymphoid cells in the gut mucosa and low concen- mucosal invasion by Biﬁdobacterium or Lactobacillus species trations of serum immunoglobulins. Exposure to commensal was not detected21. Moreover, Macfarlane and coworkers22 microbes rapidly expands the number of mucosal lymphocytes observed that numbers of adherent non-invading biﬁdobacteria and increases the size of germinal centres in lymphoid fol- were lower in rectal biopsies from ulcerative colitis patients licles. Immunoglobulin producing cells appear in the lamina than controls.

propria, and there is a significant increase in serum immuno- , subject to the Cambridge Core terms of use, available at globulin concentrations11. Most interestingly, recent findings suggest that some commensals play a major role in the induc- Prebiotics tion of regulatory T cells in gut lymphoid follicles12. Regulat- ory pathways mediated by regulatory T cells are essential A healthy or ‘balanced’ microbiota has been considered to be one that is predominantly saccharolytic and comprises signifi- homeostatic mechanisms by which the host can tolerate the 23 massive burden of innocuous antigens within the gut or on cant numbers of bifidobacteria and lactobacilli . Inulin and other body surfaces without responding through inflammation. oligofructose are prebiotic carbohydrates that resist digestion by intestinal and pancreatic enzymes in the human gastrointestinal tract and are fermented by bacteria living in the intestinal Bacteria and inflammatory bowel disease ecosystem24. When administered in adequate amounts, these The mechanisms of regulation and tolerance of bacterial anti- prebiotics increase saccharolytic activity within the gut and gens in the gut microbiota seem to be altered in subjects with promote selectively the growth of bifidobacteria. Numerous studies have shown an increase in counts of bifidobacteria in IBD. The normal mucosal defence is based mainly on the pro- 7,25 British Journal ofduction Nutrition of IgA antibodies that are secreted into the gut lumen faeces from subjects consuming inulin or oligofructoses . Moreover, oral intake of inulin and oligofructoses increases and neutralize microbes in the lumen, thus avoiding mucosal https://www.cambridge.org/core/terms inflammation13,14. In IBD, however, mucosal production of IgG antibodies against intestinal bacteria is highly increased, and mucosal defence relies on both IgG mediated responses within the tissue and hyper-activated lymphocytes in the lamina propria reacting against bacterial antigens13 – 15. These events result in inflammation and tissue injury. The altered immune response is not specifically targetted towards a single group of potential pathogens, but involves a large and undefined number of commensal species belonging to the common enteric

microbiota. A microbial imbalance in the gut ecosystem could . explain the abnormal reactivity of the mucosal immune system https://doi.org/10.1017/S0007114507832958 against enteric bacteria. Several studies have shown that the composition of the faecal microbiota differs between subjects with IBD and healthy con- trols16. Molecular studies show that a substantial proportion of faecal bacteria (up 30 to 40 % of dominant species) in patients with active Crohn’s disease or ulcerative colitis belong to phylo- genetic groups that are unusual in healthy subjects17. These remarkable changes could be secondary to disease activity but

they are not observed in patients with infectious diarrhoea. On Fig. 1. The faecal microbiota of patients with Crohn’s disease contains a the other hand, studies have shown reduced diversity of bacteria reduced proportion of Firmicutes. The graph shows data from Manichanh species in both faecal and mucosa-associated communities in and coworkers (ref 18) and represents number of phylotypes per division in 6 patients with IBD18,19. Manichanh and coworkers18 employed healthy persons and 6 patients in clinical remission. Downloaded from

Prebiotics in inﬂammatory bowel diseases S87

numbers of bifidobacteria and lactobacilli in the mucosa- the same DSS model30. The prebiotic alone or in combination https://www.cambridge.org/core associated communities of the human colon. Langlands with B. infantis strains improved significantly the disease et al.26 showed that bifidobacteria and lactobaciilli numbers activity indexes and decreased colonic myeloperoxidase could be increased more than 10-fold in biopsy mucosal speci- activity, as well as expression of inflammatory mediators. mens of the proximal and distal colons in subjects fed 15 g of Interestingly, bacterial translocation to mesenteric lymph a prebiotic mixture containing inulin and oligofructose for nodes and liver decreased significantly in rats treated by 2 weeks. Likewise, a study with ulcerative colitis patients prebiotic, probiotic or the combination of both (synbiotic) as receiving a synbiotic preparation with a Bifidobacterium compared to colitis controls. The authors concluded that oligo-

strain and oligofructose-enriched inulin showed that counts fructose and inulin as well as the Bifidobacterium strains . IP address: of bifidobacteria on the rectal mucosa increased 42-fold27. tested prevented bacterial invasion and had an anti-inflamma- Hypothetically, by increasing the number of ‘friendly’ bac- tory effect in this model. teria on the mucosal surface, inulin and oligofructose could Chronic inflammatory lesions can be induced in the distal improve the barrier function in IBD and prevent mucosal colon by a single intracolonic administration of trinitro-ben- 170.106.33.14 colonization by aerobic enterobacteria able to invade. This zene sulphonic acid (TNBS) diluted in ethanol (usually 20 hypothesis has been tested in a considerable number of to 50 mg TNBS in 30 to 50 % ethanol), using a rubber cannula.

experimental studies using different animal models of IBD. The effect of oligofructose has been tested in the TNBS model , on 31

of colitis . Oral administration of oligofructose signiﬁcantly 02 Oct 2021 at 05:32:58 reduced intracolonic pH, macroscopic lesion scores, and Experimental models of inﬂammatory bowel disease tissue myeloperoxidase activity in TNBS treated rats. In The effect of the prebiotic inulin has been tested in the rat addition, oligofructose increased the concentration of lactate model of colitis induced by the chemical dextran sodium sul- and butyrate as well as counts of lactic acid bacteria in phate (DSS)28. Oral administration of DSS over 3 to 5 days caecal contents. In subsequent ancillary experiments, these

induces direct toxicity against colonic epithelial cells that investigators demonstrated that a direct intracaecal infusion , subject to the Cambridge Core terms of use, available at results in dysfunction of the mucosal barrier with increased of lactic acid bacteria together with short chain fatty acids permeability to large size molecules29. These events are fol- was necessary to reproduce the anti-inflammatory effects of lowed by crypt destruction and loss of height of the intestinal oligofructose. They concluded that fermentation of the prebio- villi, with subsequent bacterial invasion and mucosal inflam- tic by lactic acid bacteria was the principal mechanism mation. In the rat, daily oral administration of inulin increased mediating the anti-inflammatory effect. counts of indigenous lactobacilli in the caecal lumen and Further experimental work evaluated the anti-inflammatory reduced the intracolonic pH. In rats exposed to DSS to effects of inulin and oligofructose in the transgenic HLA-B27 32 induce colitis, treatment with oral inulin reduced significantly rat model of spontaneous colitis . Rats transgenic for the tissue myeloperoxidase activity, an index of neutrophil infil- human HLA-B27–beta2-microglobulin gene spontaneously tration, and mucosal release of inflammatory mediators. develop immune-mediated colitis of variable severity at 2-4 Furthermore, inulin-fed rats showed a reduced extent of months of age. The disease is characterized by non-bloody damaged mucosa and decreased severity of crypt destruction. diarrhoea and marked inflammatory infiltration of the caecal 32 Histological damage scores were significantly lower in inulin and colonic mucosa. Hoentjen and coworkers tested a mix- British Journal of Nutrition treated rats than in controls (Fig. 2). Treatment with oral inulin ture of oligofructose and inulin in this model of spontaneous

was equally effective whether started prior to or during colitis, and observed a significant anti-inflammatory effect in https://www.cambridge.org/core/terms exposure to DSS. rats fed with the prebiotic mixture. Prebiotic treatment The effect of oligofructose and inulin alone or in combi- reduced gross morphological scores and histological grading nation with probiotic bifidobacteria was recently tested in of the lesions. In addition, prebiotic treatment reduced the expression of pro-inflammatory cytokines such as IL-1b, but enhanced the expression of regulatory type cytokines (TGF-b). The effects of the prebiotic lactulose have also been tested in some animal models of intestinal inflammation. Mice deficient of the IL-10 gene spontaneously develop colitis. In

the neonatal period, these knockout mice have a decreased . level of Lactobacillus species in the colon and an increase https://doi.org/10.1017/S0007114507832958 in adherent and translocated bacteria33. Oral administration of lactulose was shown to normalize counts of lactobacilli in faeces and prevented the development of colitis. Likewise, protective effects of lactulose have been demonstrated in the DSS and TNBS models34,35. Taken together, all these experimental data give a strong indication of the anti-inﬂammatory effects of prebiotics in a wide range of animal models of IBD.

Fig. 2. Scores of colonic mucosal lesion (solid columns, left ‘y’ axis) and tissue content of myeloperoxidase (MPO, open columns, right ‘y’ axis), a Clinical studies marker of leukocyte inﬁltration, in rats with colitis induced by DDS. Daily administration of 400 mg inulin by oral gavage signiﬁcantly reduced lesion A randomized, placebo-controlled, double-blind, crossover scores and myeloperoxidase content in colonic tissue (see reference 28). clinical trial tested the effect of inulin in patients with chronic Downloaded from

S88 Francisco Guarner

pouchitis36. This clinical condition is characterized by chronic with mesalazine as maintenance therapy or no drug, and pre- https://www.cambridge.org/core mucosal inflammation of the ileal pouch-anal anastomosis in sented to the hospital for relapse of mild-moderate activity. patients that have had a total colectomy. The ileal pouch is They were treated with mesalazine (3 g/day) and randomly surgically constructed in order to function as a faecal reser- allocated to receive either oligofructose-enriched inulin voir. The inflammatory disorder impairs the function of the (12 g/day) or placebo (12 g/day of maltodextrin) for two reservoir and results in persistent diarrhoea with mucus and weeks. The primary endpoint was the anti-inflammatory blood. Twenty patients with mild disease activity entered the effect of the prebiotic as assessed by objective, non-invasive trial and were randomized to begin with either placebo or markers of intestinal inflammation, i.e. faecal concentration

inulin (24 g per day) for three weeks, using a double-blinded of calprotectin. Calprotectin is a protein found in granulocytes . IP address: crossover design with a washout period of four weeks. Com- that resists metabolic degradation and can be measured in pared with placebo, dietary supplementation with inulin sig- faeces. Interestingly, at day 7, an early significant reduction nificantly reduced endoscopic and histological parameters of of calprotectin was observed in the group receiving oligofruc- inflammation of the mucosa of the ileal reservoir (Table 1). tose-enriched inulin but not in the placebo group. At the end 170.106.33.14 The effect was associated with an increase in faecal butyrate of the study period, disease activity scores were significantly and a decrease in the counts of Bacteroides in faeces. reduced in the two groups. Use of this prebiotic may improve 27

Furrie et al. reported a randomized, placebo-controlled, response to medical therapy with mesalazine, but this point , on

double-blind clinical trial in two parallel groups of patients needs further investigation in a trial with adequate number 02 Oct 2021 at 05:32:58 with ulcerative colitis. Eligible patients had mild disease of patients. activity and were on stable medication. Eighteen patients Prebiotics have also been tested in Crohn’s disease. In a were randomized to receive for a period of 1 month either a small open-label trial, 10 patients with active ileo-colonic synbiotic preparation (oligofructose-enriched inulin at 12 g Crohn’s disease were given 15 g of oligofructose per day for per day, and Biﬁdobacterium longum at 200 billion colony form- 3 weeks38. All but two patients exhibited a decline in the

ing units per day) or placebo (maltodextrin). Synbiotic treat- Harvey Bradshaw index of disease activity after three weeks , subject to the Cambridge Core terms of use, available at ment induced significant reduction of mucosal expression of on oral oligofructose, and the group as a whole showed a sig- proinflammatory cytokines (TNF-a, IL-1b) and inducible nificant fall in disease activity as compared to baseline. There beta-defensins. Histological examination of biopsies showed was a significant increase in bifidobacteria numbers in faeces marked decrease in inflammatory cell infiltrate and crypt but not in rectal biopsies. However, this study did not include abscesses in patients receiving the synbiotic, together with a placebo-control group. A controlled study in Crohn’s disease improved sigmoidoscopy scores and clinical activity indices, patients with appropriate sample size is now being performed but differences were not significant due to the reduced by the same group of investigators. number of patients enrolled. Taken together, experimental and clinical data so far sup- The effect of oligofructose-enriched inulin in patients with port the hypothesis that prebiotics such as inulin and oligo- active ulcerative colitis was recently tested in a randomized, fructose can offer an opportunity to prevent or mitigate placebo-controlled, double-blind pilot trial with two parallel intestinal inflammatory lesions in human Crohn’s disease, groups37. Eligible patients had been previously in remission ulcerative colitis, and pouchitis. Controlled clinical trials of appropriated sample size are still needed to confirm this British Journal of Nutrition hypothesis.

Table 1. Effect of Dietary Inulin Supplementation on Pouchitis Disease https://www.cambridge.org/core/terms Activity Index (PDAI)

Placebo Inulin P Conﬂict of interest statement

Clinical score Some of the work described in the article was performed in the Stool frequency 0·53 (0·19) 0·47 (0·15) 0·65 (NS) author’s institution, Digestive System Research Unit, which is Rectal bleeding 0·05 (0·06) 0·05 (0·06) 0·10 (NS) supported in part by grants from Generalitat de Catalunya Fecal urgency/abdominal 0·68 (0·18) 0·47 (0·19) 0·16 (NS) (RE: 2001SGR00389) and Instituto de Salud Carlos III (Ciber- cramps Fever 0 (0) 0 (0) 0·10 (NS) ehd, Spain). The author is member of the Beneo Scientific Total clinical sore 1·26 (0·29) 1·00 (0·27) 0·17 (NS) Committee sponsored by Orafti (Tienen, Belgium), a company Endoscopic score that produces prebiotics. . Edema 0·16 (0·09) 0 (0) 0·08 (NS) https://doi.org/10.1017/S0007114507832958 Granularity 0·05 (0·06) 0·05 (0·06) 1·00 (NS) Friability 0·32 (0·12) 0·16 (0·09) 0·18 (NS) References Loss of vascularity 0·05 (0·06) 0·11 (0·08) 0·56 (NS) Mucous exudates 0·32 (0·12) 0·05 (0·06) 0·03 1. Loftus EV (2004) Clinical epidemiology of inflammatory bowel Ulceration 0·58 (0·12) 0·58 (0·12) 1·00 (NS) disease: incidence, prevalence, and environmental influences. Total endoscopic score 1·47 (0·32) 0·95 (0·22) 0·04 Gastroenterology 126, 1504–1517. Histologic score 2. Sawczenko A, Sandhu B, Logan R, Jenkins H, Taylor C, Mian S Polymorph infiltration 1·44 (0·15) 1·11 (0·14) 0·05 (NS) & Lynn R (2001) Prospective survey of childhood inflammatory Ulceration per 1·17 (0·13) 1 (0) 0·18 (NS) bowel disease in the British Isles. Lancet 357, 1093–1094. low-power field Total histologic score 2·61 (0·26) 2·11 (0·14) 0·04 3. Strober W, Fuss I & Mannon P (2007) The fundamental basis of Total PDAI score 5·39 (0·62) 4·05 (0·44) 0·01 inflammatory bowel disease. J Clin Invest 117, 514–521. 4. Garcıá-Lafuente A, Antolıń M, Guarner F, Crespo E, Salas A, Data are means and standard error of the mean, in brackets, and were published Forcada P, Laguarda M, Gavalda´ J, Baena JA, Vilaseca J & by Welters and coworkers (ref. 36). NS ¼ not significant. Malagelada JR (1997) Incrimination of anaerobic bacteria in Downloaded from

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